JP2000121043A - Combusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To forcibly suppress the pressure variation at a downstream side and prevent vibration combustion, by providing a detecting means for detecting vibration at a downstream of a fuel feeding portion, and, when the vibration is detected, by controlling an air supplying portion so that combustion air is supplied with its amount being varied with a frequency which is behind the frequency of the vibration. SOLUTION: A fuel gas fed from a fuel feeding portion 14 and combustion air supplied from an air supply portion 15 are mixed in a mixing portion 11, followed by regulating the pressure so as to produce a mixed gas having a given pressure, at the time of operating a combusting device 10. A combustion chamber 13 and a heat exchanger in a heat exchanging/discharging portion 16 are heated by combusting the mixed gas by means of a burner 12, thereby heating a fluid. A control unit 18 controls the amount of the fuel gas to be fed in accordance with the required quantity of heat, and when a pressure sensor 17 detects a pressure variation of the mixing portion 11, a supply system of the combustion air, that is, the number of revolution of a fan, is controlled on the basis of the pressure variation. Thus, a statically determinate control of the pressure variation is conducted, thereby forcibly suppressing the pressure variation at a downstream side of the fuel feeding portion 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus provided with a heat exchanger such as a water heater or a blower / heater.

[0002]

2. Description of the Related Art Conventionally, such a combustion apparatus is configured as shown in FIG. In FIG. 5, a combustion device 1 includes a housing 2 having a lower vent 2a and an upper exhaust pipe 2b, and an intermediate portion in the housing 2.
A mixing section 3, a burner 4, and a combustion chamber 5 arranged in order from below, and a fuel supply section 6 for supplying fuel gas into the mixing section 3.
And an air supply unit 7 for supplying combustion air into the mixing unit 3
And a heat exchanger 8 disposed in the combustion chamber 5.

The mixing section 3 mixes the fuel gas supplied from the fuel supply section 6 and the air supplied from the air supply section 7 to generate an air-fuel mixture and regulates the air-fuel mixture to a predetermined pressure. It has become. The burner 4 has a plurality of flame ports 4a for burning the air-fuel mixture regulated in the mixing section 3, and is formed from the flame holes 4a into the combustion chamber 5 by the combustion of the air-fuel mixture. The heat exchanger 8 in the combustion chamber 5 is heated by the flame. The combustion chamber 5 has a lower end connected to the burner 4 and an upper end connected to the exhaust pipe 2 b of the housing 2.
Exhaust gas generated by combustion in the combustion chamber 5 is discharged from the exhaust stack 2b.
Is discharged to the outside via the.

[0004] The fuel supply section 6 is supplied from a fuel gas source (not shown) by, for example, an electromagnetic on-off valve 6a and an electromagnetic control valve 6b.
The fuel gas is supplied from the nozzle 6c at the tip through the mixing section 3
It is designed to be supplied inside. The air supply unit 7 is constituted by, for example, a DC fan, and supplies combustion air into the mixing unit 3 by its rotation. Further, in the case of a water heater, for example, the heat exchanger 8 has a water supply pipe routed into the combustion chamber 5,
The water flowing in the water supply pipe is heated by the combustion of the air-fuel mixture to be heated, and the hot water is sent from the outlet.

[0005] According to the combustion apparatus 1 having such a configuration, the fuel gas supplied from the fuel supply section 6 and the combustion air supplied from the air supply section 7 are mixed in the mixing section 3 and the pressure is regulated. As a result, an air-fuel mixture having a predetermined pressure is generated. The air-fuel mixture burns in the burner 4, so that a flame due to the combustion is formed from the flame opening 4 a of the burner 4 into the combustion chamber 5. Therefore, the combustion chamber 5 is heated by the flame, and the combustion chamber 5
The heat exchanger 8 disposed therein is also heated, and the fluid flowing in the heat exchanger 8 is heated and sent out.

[0006]

However, in the combustion apparatus 1 configured as described above, oscillating combustion may occur due to pressure fluctuation due to a combustion reaction. As a countermeasure against such combustion vibration, Japanese Patent Laid-Open Publication No.
There is a combustion device disclosed in No. 302022. The combustion device according to the present invention captures pressure fluctuations caused by combustion vibrations, detects the pressure fluctuations, controls the rotation of the fan of the blower that supplies the combustion air, increases the air amount, and reduces the vibrations once the vibrations have subsided. , To suppress vibration. However, in such a method, the control is not performed according to the vibration, and the effect cannot be expected much.

[0007] Such oscillating combustion is caused by pressure fluctuations in the mixing section 3, the burner 4 and the combustion chamber 5 downstream of the fuel supply section 6 and the air supply section 7 as shown in FIG. 6. Here, the pressure fluctuation in the combustion chamber 5 is as shown in FIG.
As shown in (A), for a given pressure P, the fluctuation width ΔP
Fluctuates periodically. On the other hand, the pressure in the upstream part of the fuel supply unit 6 and the air supply unit 7 (that is, the gas supply pressure of the fuel gas and the atmospheric pressure of the combustion air) are almost constant. Accordingly, the supply amounts of the fuel supply unit 6 and the air supply unit 7 also change as shown in FIG. 7B due to the above-described pressure fluctuations of the respective units on the downstream side, and thus the combustion amount changes. .

As a result, the heat generation rate of the burner 4 also fluctuates as shown in FIG.
Will cause further fluctuations in the internal pressure. And, by transmitting this pressure fluctuation to the upstream side,
The pressure in the burner 4 also fluctuates, and these pressure fluctuations cause vibration noise, and also cause resonance with the housing 2 and the mixing section 3, the burner 4, the combustion chamber 5, the heat exchanger 8, etc., which constitute the apparatus. There is a problem that vibration noise is generated. Therefore, conventionally, the dimensions of each part such as the burner 4, the combustion chamber 5, and the heat exchanger 8 are changed in order to change the natural frequency, but a design change is required. There is a problem that the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a combustion apparatus in which the fluctuation in pressure on the downstream side is forcibly suppressed to prevent the occurrence of oscillating combustion. The purpose is.

[0010]

According to the first aspect of the present invention, there is provided a combustion chamber having a burner, a heat exchanger heated by the burner, a fuel supply unit for supplying fuel gas, An air supply unit that supplies combustion air, a mixing unit that mixes and regulates fuel gas and combustion air from the fuel supply unit and the air supply unit and sends the mixture to the burner, and a vibration downstream of the fuel supply unit A combustion device comprising: a detection unit for detecting; and a control unit that, when the detection unit detects the vibration, controls the variable amount of combustion air to be supplied in a cycle delayed from the cycle of the vibration. Is achieved by

The invention according to claim 2 is characterized in that the control section is configured to variably supply the amount of combustion air at a cycle delayed by a half cycle with respect to the cycle of vibration. I do.

Preferably, the detecting means is a pressure sensor for detecting a pressure fluctuation.

The invention according to claim 4 is characterized in that the detecting means is preferably a pressure sensor for detecting a pressure fluctuation in the mixing section.

The invention according to claim 5 is characterized in that the detection means is preferably a pressure sensor for detecting a pressure fluctuation in the burner.

Preferably, the detecting means is a pressure sensor for detecting a pressure fluctuation in the combustion chamber.

According to the first aspect of the present invention, when the oscillating combustion occurs in the apparatus, the vibration that occurs at a location where a pressure fluctuation occurs in the mixing section, the combustion chamber, the burner, or the like downstream of the fuel supply section is detected. Detected by means. Then, with respect to the cycle of the vibration detected by the detecting means, the supply amount of air necessary for combustion is variably supplied by, for example, controlling the number of revolutions of a combustion fan in a cycle delayed from the cycle.
This makes it possible to predict the pressure fluctuation and supply the combustion air at a timing at which the fluctuation converges.

More specifically, for example, according to the configuration of the second aspect, the control unit variably supplies the amount of combustion air in a cycle delayed by a half cycle with respect to the cycle of the vibration. ,
On the basis of the detection result of the detection means, the control unit is configured to supply the pressure during the period from the time when the detected pressure is about to increase to the time when the pressure is increased to the maximum and then the pressure is decreased. Since the air volume is gradually reduced, the average pressure is low until the detected pressure is about to drop, the pressure drops to the lowest pressure, and then gradually rises, so the supply air volume gradually increases. The pressure fluctuation can be converged by controlling the pressure fluctuation.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIG. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 is a block diagram showing an embodiment of a combustion apparatus according to the present invention, and FIG. 2 is a system diagram in the case where such a combustion apparatus is configured as a water heater. In FIG. 1, a combustion device 10 includes a fuel supply unit 14 that supplies a fuel gas, a mixing unit 11, a burner 12 and a combustion chamber 13 that combust the mixture, and combustion air in the mixing unit 11 and the combustion chamber 13. Air supply unit 15 for supplying air and combustion chamber 13
A heat exchanger disposed at an upper portion of the fuel cell, an exhaust unit 16 for discharging combustion exhaust to the outside, a detecting unit 17, and a control unit 18
And

These configurations, for example, when configured as the water heater of FIG. 2, are as follows. The burner 12 is, for example, a burner unit containing a large number of Bunsen-type press burners and the like, and each burner has a plurality of flame openings for burning the air-fuel mixture from the mixing section 11. The flame 12a
The heat exchanger 21 is heated by a flame formed toward the inside of the combustion chamber 13.

The fuel supply unit 14 draws in fuel gas from the outside of the device, and supplies an electromagnetic on-off valve 14a and an electromagnetic control valve 1
The burner 12 is supplied to the burner 12 via 4b. The mixing unit 11 forms a mixture by premixing the fuel gas supplied from the fuel supply unit 14 and the primary air supplied from the air supply unit 15. This air-fuel mixture is regulated to a predetermined pressure by a rectifying means or a pressure regulating unit provided before the flame port 12a of the burner 12, for example. In the burner 12, when the air-fuel mixture ejected from the flame port 12 a burns, secondary air for combustion is supplied from the surroundings, and the combustion exhaust gas is discharged from the exhaust stack 16.

The combustion chamber 13 accommodates the burner 12 and has a heat exchanger 21 disposed above the burner 12. The exhaust gas generated by the combustion in the combustion chamber 13 passes through the heat exchanger 21 and is further discharged to the outside via the exhaust pipe.

The fuel supply section 14 supplies a fuel gas into the mixing section 11 from a fuel gas supply source. The air supply unit 15 is constituted by, for example, a DC fan, and the rotation thereof causes the mixing unit 11 to rotate.
The inside is supplied with combustion air. further,
The heat exchanger 21 is provided with a water supply pipe 21a for drawing water from outside of the appliance, and the water supply pipe 21 is continuous with the water pipe routed to the heat exchanger 21 in the combustion chamber 13. . The water flowing in the water supply pipe is heated by the heat exchanger 21 by the combustion of the air-fuel mixture described above,
It is heated and supplied from the hot water supply pipe 21b.

As the pressure detecting means, for example, a pressure sensor 17 is used. In this case, the pressure sensor 17 is set in, for example, the mixing unit 11 for premixing the fuel gas and the primary air for combustion. Here, when the combustion device 10 generates Helmholtz-type vibration with its combustion, it is considered that the same vibration is generated at any point downstream of the fuel supply unit 14. For this reason, in the present embodiment, it is noted that the same pressure vibration can be observed in all the places where the vibration is generated downstream of the fuel supply unit 14.
May be arranged at any of the vibration generating locations downstream of. Therefore, the location where the pressure sensor 17 is set may be, for example, the burner 12, the combustion chamber 13, or the like, in addition to the mixing unit 11.

The combustion device 10 as the water heater in FIG. 2 is configured as described above, and is represented as a block configuration as shown in FIG. In the combustion device 10 of FIG. 1, the fuel supply system 14 corresponds to the fuel supply means 14 of FIG. The pressure regulating / mixing unit 11 corresponds to the mixing unit in FIG. 2 and the rectifying means in the burner. The burner 12 corresponds to the burner or the burner unit 12 shown in FIG. 2, and the combustion chamber 13 and the heat exchange / exhaust units 21 and 16 correspond to the combustion chamber 1 shown in FIG.
3, corresponding to the heat exchanger 21 and the exhaust pipe 16, respectively. The combustion air supply system 15 is a fan 15 shown in FIG.
It corresponds to.

Further, the control unit 18 of FIG. 1 controls the fuel supply unit 14 based on the fluctuation of the pressure detected by the pressure sensor 17 of FIG. 2 as a pressure detecting means. When the pressure is low, the supply amount of the fuel gas is decreased. For this reason, pressure fluctuations in the mixing section 11 downstream of the fuel supply section 14 are suppressed, and as a result,
Fluctuations in the pressure of the combustion chamber 13 are also suppressed, and fluctuations in the heat generation rate due to combustion in the burner 12 are also suppressed.

The combustion device 10 according to the present embodiment is configured as described above. The fuel gas supplied from the fuel supply unit 14 and the combustion air supplied from the air supply unit 15 are mixed in the mixing unit 11. , And the pressure is adjusted to generate an air-fuel mixture having a predetermined pressure. The air-fuel mixture burns in the burner 12, so that a flame due to the combustion is formed from the burner 12 into the combustion chamber 5. Accordingly, the combustion chamber 13 is heated by the flame, the heat exchanger in the heat exchange / exhaust portion 16 is also heated, and the fluid such as water and air flowing in the heat exchanger is heated, and the combustion chamber 13 is heated to the outside. Will be sent. Further, the exhaust gas in the combustion chamber 5 passes through the exhaust pipe of the heat exchange / exhaust unit 16,
It will be discharged outside.

The control unit 18 controls the supply amount of the fuel gas according to the required amount of heat. Here, when the pressure sensor 17 detects a pressure change of the mixing unit 11, the control unit 18 determines a combustion air supply system, specifically, based on the pressure change.
By controlling the number of revolutions of the fan 15, static pressure fluctuation control is performed, and pressure fluctuation downstream of the fuel supply unit 14 is forcibly suppressed. As a result, the combustion combustion of the combustion device 10 is suppressed, and the vibration noise is eliminated.

FIGS. 3 and 4 are explanatory diagrams showing a specific control method of the fan 15 described above. FIG. 3 shows a state where the combustion of the combustion device 10 is performed normally and the output of the pressure sensor 17 is stable. In the drawing, a line indicated by L is a line set as a limiter in the control unit 18, for example, and when the limiter value L is exceeded, the fluctuation stabilization control of the fan 15 according to the present embodiment is performed. As shown in the upper part of FIG.
7, when the output value SV fluctuates and exceeds the limiter value L, the control unit 18 starts the static stabilization control.

Here, the fluctuation of the detection value SV of the pressure sensor 17 is a periodic fluctuation as described with reference to FIG. The rotation speed of the fan 15 is changed at a timing of 1 / 2T which is later than the cycle T. That is,
As shown in FIG. 4, the control unit 18 detects the fluctuation of the detected pressure SV of the pressure sensor 17 during the time when the detected pressure SV is about to increase and during the time t1 during which the detected pressure SV increases to a maximum and then decreases. Is high on average, during this time, the supply air amount is controlled so as to gradually decrease. In addition, during the period from the time when the detected pressure SV is about to decrease to the time when the pressure is reduced to the lowest pressure and until the time when the detected pressure SV is gradually increasing, the average pressure is low at t2, so that the supply air amount is gradually increased. I do. As described above, by periodically controlling the fan rotation speed, it is possible to perform control so that the pressure fluctuation gradually converges.

As described above, according to the above-described embodiment, when the pressure fluctuation occurs downstream of the above-described fuel supply unit 14, the control unit 18 performs, for example, 1/2 of the fluctuation period.
By controlling the rotation speed of the fan 15 with the delayed cycle, the pressure fluctuation downstream of the fuel supply unit is suppressed, and is kept substantially constant. As a result, vibration combustion is suppressed over the entire period during combustion, and vibration noise is eliminated. That is, in other words, the vibration combustion can be suppressed by changing the supply amount of the combustion air at the same frequency as the vibration of the vibration combustion and shifted by a half cycle from the vibration.

In the above-described embodiment, the pressure sensor 17 is configured to detect the fluctuation in the pressure of the mixing section 11 as the vibration on the downstream side of the fuel supply section 14. However, in FIG. As shown by, the pressure fluctuation of the burner 12 may be detected, or the pressure fluctuation of the combustion chamber 13 may be detected as shown by a chain line in FIG. In either case, the burner 12 or the combustion chamber 1
The vibration on the downstream side of the fuel supply unit 14 is detected via the pressure fluctuation of 3, and the control unit 18 can control the fuel supply unit 14 so as to suppress the vibration. Also,
In the above-described embodiment, the pressure sensor 17 is provided as a means for detecting the vibration, and the vibration is detected based on the pressure fluctuation detected by the pressure sensor 17, but is not limited thereto. It is clear that other detection means can be employed as long as vibrations due to combustion can be directly or indirectly detected.

[0033]

As described above, according to the present invention, it is possible to provide a combustion apparatus in which oscillating combustion is prevented from occurring by forcibly suppressing downstream pressure fluctuation.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a configuration of an embodiment of a combustion device according to the present invention.

FIG. 2 is a system diagram of a combustion device constituted by a water heater as an example of the combustion device of FIG. 1;

FIG. 3 is a diagram illustrating an example of a detection result of a pressure detection unit in the combustion device of FIG. 1;

FIG. 4 is a diagram showing a state in which the combustion air is varied at a period shifted from the periodic pressure fluctuation detected by the pressure detecting means in the combustion device of FIG. 1;

FIG. 5 is a schematic sectional view showing an example of a conventional combustion device.

6 is a schematic block diagram showing the configuration of the combustion device of FIG. 5 and the principle of generation of vibration.

FIG. 7 is a graph showing changes over time in pressure, fuel supply amount, and heat generation rate in a combustion chamber in the combustion device of FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 Combustion device 11 Mixing unit 12 Burner 13 Combustion chamber 14 Fuel supply unit 15 Air supply unit 16 Heat exchange / exhaust unit 17 Pressure sensor 18 Control unit

Claims (6)

[Claims] 1. A combustion chamber having a burner, a heat exchanger heated by the burner, a fuel supply unit for supplying fuel gas, an air supply unit for supplying combustion air, a fuel supply unit and an air supply. A mixing unit that mixes and regulates fuel gas and combustion air from the unit and sends the mixture to a burner; a detection unit that detects vibration downstream of the fuel supply unit; and a vibration when the detection unit detects the vibration. And a control unit that controls the supply of the air for combustion in a cycle delayed from the cycle of (c). 2. The method according to claim 1, wherein the control unit is configured to set a period of the vibration to 1 /
2. The combustion apparatus according to claim 1, wherein the combustion air amount is variably supplied at a cycle delayed by two cycles. 3. The combustion device according to claim 1, wherein the detection unit is a pressure sensor that detects a pressure change. 4. The apparatus according to claim 1, wherein said detecting means is a pressure sensor for detecting a pressure change in the mixing section.
The combustion device according to claim 1. 5. The apparatus according to claim 1, wherein said detecting means is a pressure sensor for detecting a pressure change in the burner.
The combustion device according to claim 1. 6. The apparatus according to claim 1, wherein said detecting means is a pressure sensor for detecting a pressure change in the combustion chamber.
The combustion device according to claim 1.